1. Field of the Invention
The present invention relates to a sensing device and a sensing apparatus with an adjustable resonant wavelength, and particularly relates to a pressure sensing device and a pressure sensing apparatus having adjustable laser.
2. Description of Related Art
Through the design of different defects inside the refractive index periodic artificial meta-material having photonic band and photonic band gap effect, the refractive index periodic artificial meta-material has been widely applied in the wavelength scale in recent years, and guides, prohibits or restricts the light waves with extremely low optical loss. Compared to the traditional micro-optical system based on the total reflection effect, the building of the photonic integrated chip with various nano-optical components based on above-mentioned artificial meta-material has the advantages of lower loss, high component density, smaller integrated dimension, and so on.
Through the design of localized defect in such artificial meta-material, the nanocavity with extremely low optical loss can be formed. The resonance mode within cavity usually has the characteristics of single wavelength, high coherence, high directional radiation. Currently, such nanocavity has been adapted to achieve the optical components such as filters, switches, buffers, light-emitting diodes, lasers, solar cells, etc.
However, due to the compromise of the process simplicity and yielding requirements in manufacturing process, such nanocavity components are mostly manufactured on the two dimensional thin slab based on semiconductor or other dielectric materials. Although the nanocavity has a size close to the wavelength size, the meta-material arranged and expanded in two dimensions leads to disadvantage of extremely large device footprints of the components.
In addition, such nanocavity device based on meta-material having geometric difference with the optical waveguides commonly used in the photonic integrated chips. Generally, for achieving the low-loss optical interconnection, complicated geometric designs are needed. That is, such nanocavity device has the disadvantage of low compatibility with the traditional optical waveguide.
On the other hand, the resonant wavelength adjustability of such nanocavity devices have been widely discussed in literatures. Specifically, the wavelength adjustability mentioned herein is referred to as “reversible and repeatable wavelength adjusting”. The principle of adjusting the resonant wavelength lies in changing the resonant condition of the nanocavity through applied variables. Currently, the methods of adjusting the resonant wavelength can be divided into two ways.
The first way is changing the refractive index of the nanocavity itself or the surrounding mediums. About the change of the refractive index of the nanocavity, it can be achieved by methods of changing the temperature of the nanocavity, concentration of the injection of free carrier, and so on. About the change of the refractive index of the surrounding materials, it can be achieved by adjusting the concentrations of the refractive-index-adjustable gas and liquid, or liquid crystals able to be changed in their refractive index by voltage controlling. However, in the above methods, the range of the wavelength adjustability is usually limited by the variable range of the refractive index of the material.
The second way to achieve wavelength adjustability is directly changing the nanocavity structure. For instance, the wavelength adjustability can be achieved by the methods such as approaching the nanocavity by external perturbation (such as nano-micro-probe, micro-fiber), or changing the coupling length of the resonance mode using the microelectromechanical systems. Although these methods can obtain high wavelength adjustability, the design of complicated structures is usually needed to achieve significant change of the micro-structure. That results in their difficulty in integrating within the integrated photonic chip.
Therefore, the issue of developing the optical component with adjustable resonant wavelength having characteristics such as smaller device footprint, high compatibility with the conventional optical waveguides, and high wavelength adjustability is one of the key development priorities in the field.